Low-capacity fuse



April 26- 1927. 1,626,105

E. V. SUNDT LOW CAPACITY FUSE Filed Feb. 8. 1926 INVENTOR 6. a Sandi ATTORNEYS;

Patented Apr. 26, 1927.

EDWARD V. SUN DT, OF CHICAGOyILLINOISL LOW-CAPACITY FUSE.

Application filed February My invention relates to improvements in low-capacity fuses, and it consists in. the combinations, constructions, and arrangements herein described and claimed.

An object of my invention is to provide a low-capacity fuse which makes use of metal of high resistance and therefore quickly heated for fusing a metal of low melt1ng temperature, whereby a fuse is provided that will operate at low current-carrying capacities.

A further object of my invention is to provide a device of the type described whlch is extremely simple in construction, and 1n which the fuse wires are connected to each other in a manner to provide a good electrical connection, the connection of the wires also effecting a quick break between the wires when the fuse operates.

A further object of my invention is to provide a device of the type described in which the fuse may be readily renewed by the simple addition of a small piece of fusible wire.

Other objects and advantages will appear in the following specification, and the novel features of the invention will be particularly pointed out in the appended claims.

My invention is illustrated in the accompanying drawings, forming part of thls application, in which- Figure 1 is a sectional view of the casing showing the parts operat-ively connected tor gether,

Figure 2 is a top plan view of Figure 1, and

Figure 3 is an enlarged sectional view along the line 33 of Figure 1.

The device is designed primarily to oper ate at low current-carrying capacities for use in radio work, experimental work, and where sensitive and inexpensive electrical, equipment is used. The device comprises a casing 1 in which I dispose two insulating strips 2 and 8. The casing 1 is preferably made of insulating material also. The strips 2 and 3 are connected to each other by eyelets 4 and 5 and are spaced from each other by soldering lugs 6 and 7 and washers 6' and 7 see Figure 3. The lugs have openings 8 and 9 adjacent to their free ends for receiving wires 10 and 11.

s, 1926. Serial No. 86,878.

The wires 10 and 11 constitute the fusing element. The wire 10 is made of a metal. having a low melting temperature, for example, a metal composed of a lead and a tin alloy. The wire 11, or the second part of the fuse, is made of a metal having a relatively high resistance, for example, nickel and chromium alloy, or a nichrome wire. These wires are soldered to their respective lugs 6 and 7 and are bent around each other at 12 and then have their free ends cemented or otherwise secured to the strip 3, as at 13 and 14. The wireslO and 11 are drawn taut for affording a good electrical connection between the lugs 6 and 7.

Terminal screws 15 and 16 are inserted through openings in the casing 1 and also pass through the eyelets 1 and 5. Lock nuts 17 and 18 secure the screws in place and clamp the screws tightly to the eyelets 4 and 5, whereby a good electrical connection is made. Knurled nuts 19 and 20 are also mounted upon the screws 15 and 16 for securing wires, not shown, to the terminals. In addition to the wire-securing screws 19 and 20, I dispose soldering lugs 21 and 22 between the casing 1 and the nuts 17 and 18.

From the foregoing description of the various parts of the device, the operation 1 thereof may be readily understood. The fuse is connected in a circuit and the current will flow, for example, from the terminal 15 to the lug 6, the wire 10, the wire 11, the lug 7, and then to the terminal 16. If an excessive current should be passed through the fuse, the high-resistance wire would quickly heat and would therefore aid the current in melting the low-melting tempera ture wire 10. The same tension of the wires 10 and 11, which makes a good electrical connection between the wires, now aids in quickly breaking the contact between the wires when the wire 10 is melted at 12.

This principle of fusion permits a small capacity fuse to be constructed which is easily manufactured, and which will withstand the most severe commercial requirements. The fusing element is mounted for its protection within insulating material, i. e., the strips 3 and 4 and the casing 1. The same members 15 and 16, which effect the assembly of'the fuse, also serve to con nect the fuse with the mounting 1 and t0 fusible Wire connected to one of said lugs, a

connect the fusing element with the circuit. high-resistant wire connected to the other 10 I claim: lug, said wires contacting with each other A low-capacity fuse comprising a casing, and having their free ends secured to said i insulating members disposed in said casing, insulating members, and terminals passed eyelets connecting said members together, through said casing and through said eyelugs carried by said eyelets and being dislets.

posed between said insulating members, a EDWARD V. SUNDT. 

